Commentary for Deuteronomy 15:12

כי ימכר לך IF [THY BROTHER …] BE SOLD UNTO THEE by others (not one that sells himself as a servant on account of his destitution, of which case Scripture deals in Leviticus 25:46 ff); Scripture is speaking of one whom the court has sold for a theft that he has committed. But has it not already been stated. (Exodus 21:2) “If thou buyest an Hebrew servant” and there, too, Scripture speaks of one whom the court has sold (as proved by Rashi in his comment on that verse; Mekhilta d'Rabbi Yishmael 21:2:1)?!. But the repetition was necessary because of two new points that are stated here: the one is that it is here written “or an Hebrew woman”, that she, too, like a man-servant, goes free at the end of six years of servitude — it does not mean a woman whom the court had sold, for a woman cannot be sold by the court on account of a theft committed by her, since it states, (Exodus 22:2) that the thief shall be sold “for his theft” which implies: he for his theft, but not she for her theft (Sotah 23b); — but what Scripture is speaking of here is of a woman under age whom her father has sold as a handmaid, and it teaches you here that if six years of servitude terminate before the time that she shows signs of incipient puberty she goes free. And further it mentions a new point here, viz., “thou shalt furnish him (or her) liberally” (cf. Rashi on Exodus 30:4).

ועבדך, "and he will serve you, etc." The letter ו at the beginning of this word connects it to the previous commandment. This is analogous to what our sages have taught about the word לך in the sequence כי ימכר לך, that a Jewish court is not allowed to "sell" the labour of a Jew except to another Jew. The new addition to this restriction of the court's authority is that the length of time for which the labour of such a Jew may be sold is restricted to six years.

אחיך העברי, on account of his inability to make restitution for what he had stolen.